Integrated circuitry fabrication typically involves lithographic processing to transfer patterns formed in an imaging layer to an underlying substrate material which will form part of the finished circuitry. One example process is photolithography wherein the imaging layer comprises photoresist. A form of radiant energy is passed through a radiation-patterning tool and onto the photoresist. The radiation-patterning tool is commonly referred to as mask, photomask, or reticle. The term “photomask” has traditionally been used to refer to masks which define a pattern for an entire side of a substrate, while the term “reticle” traditionally refers to a masking tool which defines a pattern for only a portion of a side of a substrate.
A reticle typically encompasses multiple die/chip areas of the substrate being patterned. The reticle and substrate bearing the photoresist are moved relative to one another such that multiple discrete exposures of the substrate through the reticle completely patterns the entire side of the substrate. The time required to completely pattern one side of a substrate for a given masking step totals the time it takes to move the reticle and substrate relative to one another in combination with the time of radiation exposure through the reticle between movements. The equipment used to accomplish such is very expensive. Accordingly, anything that can be done to reduce the time of the individual exposures would increase the throughput of the tool.
While the invention was motivated in addressing the above-identified issues, the invention is no way limited.